Method of and apparatus for treating gumlike substances



May 29, 1928. v

- G. H. CARNAHAN `METHOD OF ANDA APPARATUS FOR' TREATING GUM-LIKESUBS-TANCES Filed June 4, 1925 v Patented May 29, 1928.

- UNITED. sTA

TES PATENT OFFICE.

GEORGE H. CARNAHAN, O LONG BEACH, CALIFORNIA, ASSIGNOR TO INTERCONTI-NENTAL RUBBER PRODUCTS CORPORATION, OF WILMINGTON, DELAWARE, A COR-{PORATION OF DELAWARE.

METHOD OF AND APPARATUS FOR TREATING GUMLIKE'SUBSTANCES. i

Application tiled June 4,

This invention relates to rubber and has for its more general objects toprovide novel processes or methods of separating the ruber from itsvegetable source, novel processes or methods of treating the rubber,novel combinations and sub-combinations of instrumentalities to carrythe processes into practice, and to noved forms of rubber produced bysuch processes or methods. Other objects and advantages will appear asthe invention is hereinafter disclosed.

While the invention, or at least certain features thereof, may beapplied to other rubber or gum-.like materials, it is particularlyadapted for the removal of rubber from the guayule plant or shrub andfor the treatment. of the rubber after such removal. For this reason,and to avoid surplusage in disclosure, I shall restrict the presentdisclosure to the, removal' of rub'ber from guayule shrubs and to thetreatment of such rubber. The processes or `methods may best beexplained in conjunction with What I now consider preferred'forms andcombinations of instrumentalities for carrying'them into practice. Ishall therefore adopt that plan of disclosure and shall refer to thedrawings in which Ihave indicated, somewhat diagrammatically, in Fig. 1,the plan layout of a preferred form of plant or mill, and in. Fig. 2 avertical section of one of the agitators.

For a proper understanding of the invention I shall irst briefly andgenerally describe the guayule plant. It is an herbaceous perennial,native of Texas and Mexico,

contains resin, caoutchouc, essential oil and other materials and may beemployed to produce guayule rubber.

The guayule shrubs are deposited upon or fed to a platform conveyer-lO,then fed to and automatically carried by a belt conveyer 11 from theplatform conveyer and kdischarged into the inlet of a four-rollercrusher 12. The shrubs are brok'en up into fragments in the Crusher l2and then dis- .i charged from the' bottom of the erusher upon a bucketconveyer 13 which automatically carries `the crushed material to anagitator 14. Preferably, the material is sprayed with Water at thecrusher to settle any dust tending to rise therefrom and-to j wet thematerial and make it more suscep- 19'23. serial No. 643,141.

tible to the treatments hereinafter described. Sufiicient additionalWater is added to the material either at the crusher 12, or at theagitator 14, preferably thelatter, to provide a mixture of 3-4.5,preferably 3.5, parts by weight of Water to one part of guayulematerial, to befed to the tube mill 15. The water and guayule materialare violently agitated in the agitator 14 by means of an upwardlydirected air blast entering the bottom of the latter. The agitator 14(see Fig.

`ing period of about one-half hour. The

mixture of Water and material is automatically discharged from theagitator 14 into the scoop box 16 of the tube mill 15 which is providedwith a scoop 17 for automatically scooping up the mixture in the scoopbox and feeding it into the inlet trunnion of the mill 1'5. The mill '15is continuously rotated about its longitudinal axis and contains a.multiplicity Aot grinding elements, preferably in the form of flint orDanish pebbles having a diameter of from 3.5 to 4.0 inches. The mill 15is designed primarily for grinding or disintegrating the guayulematerial. The material is subjected to the abrasive, crushing anddisintegrating action ofthe pebbles within the mill 15 and is separatedinto three components; i. e., rubber, bagasse, and

.lighter `material generally known as cork.

box 18, is discharged from the latter into the scoop box 19 of the tubemill'20 which is provided with a scoop 21 for causing the mixtureautomatically to enter the inlet trunnion of the said mill 20. Water isadded to the mixture, `preferably in the pebble box 18, to bring theratio of water to guayule mixture up to from 6-8 to. 1, pre 'erably' 7to 1. The mill 20 contains grinding media preferably in the form offiint or Danish pebbles having an average diameter of 3 inches. In themill 20 theaction upon the material is primarily to agglomerate theparticles of rubber, although there will be a certain amount lofdisintegrating and cleaning action' as set forth in connection with themill 15.

By treating guayule material in a grinding or disintegrating mill in thepresence of water, two extremely important functions,

A among others, are performed. The material is disintegrated and therubber, cork and bagasse thereby separated from each other. The rubberparticles are agglomerated. The disintegrating or grinding action isaccomplished most efficiently in the presence of a comparatively lowamount of water while the agglomerating action is accomplished mosteiieiently in the presence of a comparatively high amount of water. Theimportance and advantageous results incident to treating the materialinthe mill 15 in the presence of a comparatively low amount of water andvpreferably with comparatively large grinding media, and in the mill 20in the presence of a comparatively high amount of Water and preferablywith smaller grinding media, will therefore be appreciated.

The material dischar es from the mill 20 into a pebble box 22 w ichcatches 4and retains any pebbles accident-ally discharged from the mill20. The mixture discharged from the mill 20 consists of water, worms of5 that it will sink in water.A Therefore, in thesheets. These sheets areplaced on :au

rubber, each Aabout the size of a grain of wheat, cork and bagasse. Thismixture is discharged from the box 22 into a scrubber or agitator 23,(similar to the agitator 14), where it is subjectedto alviolentagitation and scrubbing by theA stream of air under pressure whichenters the bottom of the agitator and is directed toward the upperpart'thegof as previously described. In its passage rom the mill 20 tothe agitator 23, water is added to the mixture, preferably in the box22, to bringv the ratio of water to guayule material up to about A12to 1. The mixture is automatically elevated from the agitator 23 to asettling tank 2 5. By the time the mixture reaches the tank 25 theguayule material will not only have been substantially separated intothree components-rubber, cork, and bagasse-but the bagasse will havebecome water-logged or impregnated with water .to such an extentsettling tank 25, the lighter particles of the material; i. e., therubber and the cork, rise to the surface of the water and the bagassesettles or sinks to the bottom. The rubber and cork particles overflowfrom the tank '25' into the launder 26, whence it flows by gravity downthe trough A27' into a V-bottom settling tank 28. A settling tank 29 isshown arranged parallel to the tank 28 and has for its function toprovide an auxiliary or relief tank for the tank 28. The design is suchas to allow suicient time to enable substantially all rubber articles torise to the surface of the water w ence they are skimmed by hand,together with cork particles, into a trough 30 placed between said tanks28 and 29. screw-conveyor 31 runs in this trough 3 0 and carries therubber'and cork to the foot of the elevator 32, Where it is lautomatically picked up, carried Iup by the velevator 32 and depositedinto a bin above the heating and compression tanks 33, 33.

Sufficient alkali, such as milk of lime, is preferably added to the-mixture in the tanks 33, 33, to make the rubber harsh and toix theresin in the rubber, which is naturally acid.

The mixture of Water, rubber and cork is permitted to flow from the binabove theA said tanks 33, 33, into one or the other of the said tanksto'charge the same. After the tank 33 is charged, steam is injected intoit to bring the water to boiling temperature. The contents of the tank`are then -subjected to hydraulic `pressure of about 250 pounds for asuiicient period-say 1.5 hours--to waterlog or mpregnatethe cork withwater lto such van, extent a's toy cause -it to sink.

Among other functions, the heating of the mixture in the compressiontanks softens the fibres of the cork'and thus aids in the Waterloggingthereof. The heating also sterillzes the mixture and kills, or. rendersinert, the

enzymes and any bacteria which might otherwise give rise to subsequentfermentation.

After the charge of eachtank v33 is treated as set forth above, it isdischarged into a reservoir 34 which discharges into a beater washer 35where the mixture is given a mechanical scrubbing action whichthoroughly separates the rubber from the cork parti*- cles. The rubberparticles rise to the surface while the cork particles, which becameWaterlogged in the tanks 33, 33,*sink orset-l tle to the bottom. Therubber particles are drawn off the top of the washer 35 and iowL downthe launder 36 into the storage tanks 37. 'l'h waterlogged corkparticles are passed from the bottom of the washer 35Ito the tank 28. lv

The rubber is skimmed from the surface of the storage tanks 37 andsubjected to thel action of a series of washing rolls 38, 39, 40, whichclean, agglomerate it and roll it into trays and placed in one oranother of the vacuum driers 41. When a vacuum drier 41 has received itscharge it is supplied with steam at about 2O pounds pressure. Then thedrier is subjected to a vacuum of about 28.() inches causing water andessential oil vapors to pass ofi' from the rubber. These vapors arepassed through a condenser and the essential oil-a commercially usefulliquid-collected.

It will'be noted that I remove the essential oil from the rubber beforevit has had any sutlicient time to dissolve the resin and to causeoxidation or otherwise to cause deterioration of the rubber. In otherWords, the time interval which elapses between the crushing of anyparticular portionof guayule shrub, in the crusher 12, and the removalof the essential oil from the rubber, in the drier 41, is comparativelyshort and of no suflicient duration as to permit the essential oil-t0depreciate the rubber. This is an important feature of my invention.Prior to crushing in the machine 12 the resin, caoutchouc, and essentialoil, are in separate cells or substantially out of contact with eachother. By the crushing action in the machine 12 the cells are brokendown and it therefore becomes important to remove the essential oil fromthe rubber before any long time has elapsed. This is accomplished by myapparatus and process. l

After the above described treatment in the drier or diiers 41 the sheetsof rubber are removed and pressed into blocks or other suitable shapesfor shipment.

. In order tomemove any particlesof rubber that adhere to the bagasse,which sett-les in the tank 25 as heretofore described, and any particlesof rubber that adhere to the vaterlogged cork which' sinks in the tank28, I prefer to employ the following method and apparatus. Y

The tank 25 is provided at its bottom with a trough containing a yscrewconveyer 45 and with' a plurality of vanes or Scrapers 46, r0- tated byany suitable means, for feeding the waterlogged bagasse into theconveyer trough. The conveyer 45 automatically conveys and dischargesthe bagasse into the bottom of the elevator 47 vwhich discharges thebagasse into a chute 48 and thence into a scoop box 49. The V-bottom ofthe tank 28 terminates in a trough containing a pair of screw conveyers52, 52, whichfeed the waterlogged cork toward the center of the bottomof thettank 28 and into an elevator 53 which discharges the waterloggedcork into the elevator 47. The waterlogged vcork passes. along with thebagasse in the elevator 47. into the chutey 48 and then into the scoopbox 49. If necessary,'water is added to the bagasse, preferably in thescoop lbox 49Vto form a mixture of about six parts by" weight of waterto one part of the other material. The mixture is automatically pickedup by the scoop 50, forming a part of the tube mill 51, andautomatically fed throuvh the inlet trunnion of the latter. The tu emill 5l contains grinding media, preferably in the form of flint orDanish pebbles each about 2.5 inches in diameter, and is rotated aboutits longitudinal axis. The action of the tube mill 51 upon the material(bagasse, cork and any particles of rubber not previously removed) willbe understood in View of the foregoing description of the tube mills 15and 20. Among other functions accomplished by the tube mill 51, toagreater orA less degree, are the grinding, rubber-agglomcrating, frnbber-scrubbin g, bagasse-Wa terlogging, actions heretofore described.

The mixture of material is automatically discharged from the outlettrunnion of the tube mill 51 into a pebble or catch box 52, whichcatches and retains any pebbles discharged from the mill 51. Thematerial passes from the box 52 to the agitating tank 53, thence toelevator 54 and into the settling tank 55. The floating particles ofrubber,

and cork over-How the upper edge of the tank 55 into a launder 56 andenter the tank 28 through'a trough 0r chute 57. The water' loggedhaga-sse and waterlogged cork sink or settle in the tank 55 and areautomatically removed therefrom, as waste material, lby meansof therotating vanes 58 and screw conveyer 59 at the lower art of the tank.The rubber and cork particles,vwhich enter the tank 28 through thetrough or chute 57,' are passed into thc conveyer 31 and thensubsequently treated as described at length above in connection with therubber and cork particles which enterthe tankA 28 from the tank 25. Theinstrumentalities 52 to 59, inclusive, correspond respectively to theelements 22,23, 24, 25, 26, 27, 46 and 48 heretolfore described, andtherefore require no fur ther description. Water is preferably added tothe mixture in'the box 52 to cause the ratio of water to the othermaterial tol be about 12 to 1. The reliefof the settling tank 28 intothe tank 29 may be accomplished by means-of regulating pip'e or conduitconnections 60.

-The waterlogged bagasse and waterlogged cork,'discha'r ed from theconveyer 59, were referred to a ove as waste material. In a sense thismaterial is not wasted since I propos'e to dry it to a suiicient extentvand to employ it as fuel to feed a boiler or battery of boilers (notshown) to supply steainto the engines, or preferably single engine (notshown), vemployed to drive the crusher 12,

tube mills 15, 20, 51. thevarious conveyersf and elevators, and othermoving parts of the'- plant. The methods and apparatus -above describedare so efficient lthat the" sofcalled' Waste material discharge-d fromthe conveyer- 59 constitutes theV sole supply of fuel for operating allof the machinery employed.y

product than has heretofore been produced.'v

When Mexican guayule shrubs are employed as the raw material, `theproduct-guayule .rubber-produced by my complete process contains about20% resin, 78% pure caoutchouc, and 'substantially no essential o1l.

c Moreover, the essential oil is removed from the roduct beforedeterioration, 'otherwise inci ent to its prolonged presence, has takenplace.

In accordance with the provisions of the patent statutes, Iphave hereindescribed the principles of operation of myy inventionftogether with theapparatus which I now consider to represent theA best embodimentsthereof, but I desire to have it understood that the apparatus disclosedis only illustrative land that the invention 4or certain featuresthereof ma be carried out by .other means. Also, while it is designed touse the various features and elements in the combination described,-some of these may be altered and others omitted Without interferingwith some of the results and advantages outlined, and the inventionextends to such use.

What I claim isn 1. The process of producing rubber'from a vegetablesource which comprises grinding the source in successive stages inthepresence of water, the ratio of water to material in l one stage beingdifferent from that insanother stage.

2. The process of producing rubber from a vegetable source which.comprises subjectveo ing the source to the action of a multiplicity offreely moving elements in the presence of water to grind the source, andsubjecting the source so treated to the action of a multiplicity offreely moving elements in the presence of a larger ratio of Water toagglomeate particles of the rubber.

3. The process of producing rubber from a vegetable source which comrises finely dividing the source, grinding the source in the -presenceof a suitable quantity of'water, and subjecting the source to therubbing aetion of a multiplicity of @freely andindividually movingrelatively hard elements in thelpresenee of alarger uantity of water.

4e-.The -process of'pro ucingrubber from .a vegetable sourcewhich-,comprises agitating subjecting the source to the rubbing actionof a multiplicity of freely and individually moving relatively hardelements in the presence of a larger quantity of water.

5. The proces-s of producing rubber from a vegetable source whichcomprises finely dividing the source, agitating the source in thepresence of Water preliminary to grinding, grinding the source in thepresence of a suitable quantity ofl water, and subjecting the source tothe rubbing action of a multiplicity of freely and individually movingrelatively hard' elements in the presence of a largerquantity of water.

G. The process of producing rubber from a vegetable source whichcomprises finely dividing the source, grinding the source in thepresence of a suitable quantity of water, subjecting the source to therubbing ,action of a multiplicity of freely and individually movingrelatively hard elements in the 00 presence of a larger quantity ofWater, separating the rubber and particles of the source which arelighter' than water from the portions of the source which are heavierthan water by iiotation of the former, and subjecting the rubber tothepaction of a suitable alkali.

7. The proces-s of producing rubber from a vegetable source whichcomprises finely dividing the source, grinding the source in thepresence of a suitable quantity of water, subjecting -the source to therubbing action `of a multiplicity of freely and individually movingrelativelyhard elements in the presence of a largerquantity of Water,separating the rubber and particles of the" source which are lighterthan Water from'the porv tions of the source which. are heavier thanwater by flotation ofr the former, heating the rubber and particleswhich are li hterl than i water, subjecting the rubber an 'particles lwhich are lighter than water to Water under pressure to cause the lastmentioned particles to become heavier than Water, and sep: arating therubber from the remaining particles by scrubbing and flotation.

8. The process of producing rubber from a vegetable source whichcomprises grinding the source in the resence of a suitable quantity ofwater,J su j'ecting the source to the 120 rubbing action of amultiplicity of freely' and individually moving relatively hardelement/s in the presence of a larger uantit of water, separating therubber an part-1- cles of the source whichv are 'lighter than 125 Waterfrom the portions ofthe source which are heavier than water by flotationof' the former, separating out the rubber, and removing essential oilfrom the rubber by dise` 9. The process of producing rubber from avegetable source which comprises finely dividing the source, agitatingthe source in the presence of Water preliminary to grinding, rinding thesource in the pre-sence of a suita le quantity of Water, subjecting thesource to the rubbing action of a multiplicity of freely andindividually moving relatively hard elements in the presence of a largerquantity ot Water, agitating the source in the presence ot water,separating the rubber and particles of the source which are lighter'than Water from the portions of the source vWhich are heavier than waterby dotation ot the former, subjecting the rubber to the action ot asuitable alkali, heating the rubber :and particles which are lighterthan Water. subjecting the rubber and particles which are lighter thanwater to Water under pressure to cause the last mentioned particles tobecome heavier than Water, separating the rubber from the remainingparticles by scrubbing and flotation, and rolling the rubber intosheets.

10. The process of producing rubber from a vegetable source whichcomprises finely dividing the source, agitating the source in thepresence of Water preliminary to grind-l ing, grinding the Sources inthe presence of a suitable quantity'of Water, subjecting the source tothe rubbing action of a multiplicity of freely and individually movingrelatively hard elements in the presence of a larger quantity of water,agitating the sourcein the presence of water, separating the rubber andVparticles of the source which are lighter than water from the portionsof the source which are heavier than Water by flotation of the former,subjecting the rubber to the action of a suitable alkali, heating therubber and particles which are lighter than Water, subjecting the rubberand partlcles which are lighter than water to Water under pressure tocause the last mentioned particles to become heavier than water,separating the rubber from'the remaining-particles by scrubbing andflotation, rolling the rubber int'o sheets, removing essential oil fromthe rubber by distillation, regrinding the above mentionedheavier-than-water material of the source, agitating the last mentlonedmaterial in the presence of water, separatmg the rubber and particleslighter than Water from the-last mentioned material by dotation, andsubsequently treating the last mentioned mixture of rubber and partlcleslighter than water to substantially the same treatment set forth abovein connection with the first mentioned mixture of rubber and particlesylighter than Water separated from the source.

11. The process of treating guayule rubber which comprises subjectingthe rubber to a solution of milk of lime.

12. The process of treating guayule rubber which comprises subjectingthe rubber to a solution of milk of lime, and subsequently scrubbing therubber.

13. The method ot extracting rubber from its vegetable source whichcomprises passing the source through a tube mill in the presence ofwater, increasing the ratio of Water to source, and passing the mixturethrough a second tube mill.

14. A plant for extracting rubber from its vegetable source andcomprising in comwhich said first mentioned tube mill dis-v chargesindirectly, means for changing the volume of water intermediate saidmills, means preventingV the passage of Water dircctlvl from either millto the other, and grinding medial in said tube mills, the grinding mediain the iirst mill being of larger size than the media in the secondmill.

16. A plant for extracting rubber from its vegetable source andcomprising in combination, a tube mill, means for feeding a mixture ofWater and source to said tube mill while the latter is rotating, asettling tank which receives the discharge of said tube mill, a secondtube mill, and means for supv plying the material which settles to the'bottom of saidtank, to said second mentioned tube mill.

17. A plant for extracting rubber from its vegetable source andcomprlsing in combination, a tube mill, means for feeding a. mixture ofwater and source to said tube mill While the latter is rotating, asecond 'tube mill -into which said first mentioned tube mill discharges,a settling tank which receives` the discharge of saidv second tube mill,a third tube mill, and means l:for sup.

plying the material which settles to,V the 'i bottom of lsaid tank, tosaid third tube mill.

18. The processof treating guayule rubber which comprises-'subjectingthe rubber.

to lime.

In testimonyjvvhereofu'l hereto.k aliixi l signature.

GEORGE H. CARNAHAN.

